Changes in tumour cell selenite (75Se) affinity due to irradiation

Area of Science:

• Biochemistry
• Radiochemistry
• Oncology

Background:

• Selenium is an essential trace element with known roles in cellular processes.
• Radiation therapy can alter cellular metabolism and tissue composition.
• Understanding selenium's behavior in irradiated tissues is crucial for potential therapeutic or diagnostic applications.

Purpose of the Study:

• To investigate the impact of irradiation on the uptake and distribution of 75Se-labeled sodium selenite in rat liver and tumor tissues.
• To compare in vitro and in vivo selenium uptake in irradiated versus non-irradiated biological samples.
• To correlate experimental findings with clinical observations of selenium accumulation in patients.

Main Methods:

• Utilized radiation measuring techniques and radiochromatography to quantify 75Se uptake.
• Conducted in vitro experiments involving incubation of irradiated liver slices with selenite solution.
• Administered 75Se sodium selenite intravenously to irradiated Wistar rats bearing tumors (Ehrlich ascites and Guérin tumors) for in vivo studies.

Main Results:

• In vitro: Irradiation led to an 11% decrease in 75Se uptake in liver proteins compared to controls.
• In vivo: 75Se uptake in Ehrlich ascites tumor cells was 71% of control levels post-irradiation.
• In vivo: Accumulation of 75Se in Guérin tumor proteins was 62% of control levels after irradiation.
• Radiochromatography revealed distinct differences in selenite distribution between irradiated and non-irradiated tumors.
• Experimental results were consistent with clinical 75Se-scintigraphy showing reduced selenium accumulation post-irradiation.

Conclusions:

• Irradiation significantly impairs the uptake and retention of sodium selenite in both liver and tumor tissues.
• The observed decrease in selenium accumulation in irradiated tissues has implications for selenium's role in radiation response.
• Findings support the clinical observation of reduced selenium uptake in irradiated tissues, suggesting potential for further research in selenium's interaction with radiation therapy.